The invention relates to the use of specific materials to control the deposition or non-deposition of radionuclides of cobalt and manganese from liquid sodium.
The sodium coolant for sodium cooled fast breeder reactors becomes a carrier of radioactive isotopes which may be high temperature corrosion products, or neutron irradiation products, or the like from the various components that are in contact with the liquid sodium. The activity resulting from the corrosion product transport and subsequent deposition on primary heat transport system surfaces is a serious problem that limits access time for maintenance of system components such as pumps, pump shafts, intermediate heat exchangers, valves, flow and temperature sensors, etc. This problem may be of a more serious nature, if, during operation of the liquid metal fast breeder reactor, fuel failure occurs so that the problem is intensified due to possible fission product release.
The radionuclides that present the greatest problem include manganese-54 (.sup.54 Mn), cobalt-58 (.sup.58 Co) and cobalt-60 (.sup.60 Co). While other radionuclides may also be present and may also limit access time for maintenance purposes, the present invention is directed to the above cited specific radionuclides.
It would be desirable to eliminate or reduce the problem of radionuclide concentration in areas where maintenance of system components is required and it would likewise be desirable to control the areas in which this radionuclide deposition takes place or does not take place.